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# Compare vibrational frequencies for two calculations for C6H12 ((E)-3-methylpent-2-ene)

### A = HF/6-31G* B = MP2/6-31G*

scale factors=0.8985, 0.943
symmetry   frequency (cm-1)   reduced mass (amu)   IR Intensity (km mol-1)
mode number A B   A B diff. ratio   A B diff. ratio   A B diff. ratio
1 A A   2983 3035 -52.4 0.983   1.093 1.097 -0.004 0.996   73.44 28.62 2.566
2 A A   2975 3023 -47.5 0.984   1.090 1.101 -0.010 0.991   18.41 26.01 0.708
3 A A   2956 3018 -61.4 0.980   1.097 1.103 -0.006 0.995   14.33 21.88 0.655
4 A A   2942 3010 -68.3 0.977   1.103 1.103 -0.000 1.000   59.17 30.27 1.955
5 A A   2933 3002 -68.6 0.977   1.103 1.089 0.013 1.012   62.82 12.85 4.890
6 A A   2913 2984 -70.7 0.976   1.100 1.101 -0.002 0.999   37.99 20.35 1.867
7 A A   2908 2982 -74.2 0.975   1.097 1.101 -0.005 0.996   17.93 17.95 0.999
8 A A   2905 2960 -54.6 0.982   1.101 1.101 -0.000 1.000   35.11 15.12 2.322
9 A A   2880 2928 -48.6 0.983   1.039 1.035 0.003 1.003   39.08 22.82 1.713
10 A A   2874 2921 -46.6 0.984   1.042 1.039 0.003 1.003   18.67 14.38 1.298
11 A A   2869 2918 -49.0 0.983   1.042 1.038 0.004 1.004   66.76 29.43 2.269
12 A A   2861 2904 -43.5 0.985   1.068 1.063 0.005 1.005   39.20 28.17 1.391
scaled by     0.8985 0.943

See section III.C.1 List or set vibrational scaling factors to change the scale factors used here.
See section III.C.2 Calculate a vibrational scaling factor for a given set of molecules to determine the least squares best scaling factor.